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  <title>返回输入数组中指定列的值</title>
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    <li>返回输入数组中指定列的值</li>
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  <div id="layout-content"><div id="function.array-column" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">array_column</h1>
  <p class="verinfo">(PHP 5 &gt;= 5.5.0, PHP 7, PHP 8)</p><p class="refpurpose"><span class="refname">array_column</span> &mdash; <span class="dc-title">返回输入数组中指定列的值</span></p>

 </div>
 <div class="refsect1 description" id="refsect1-function.array-column-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="methodname"><strong>array_column</strong></span>(<span class="methodparam"><span class="type">array</span> <code class="parameter">$array</code></span>, <span class="methodparam"><span class="type"><span class="type">int</span>|<span class="type">string</span>|<span class="type">null</span></span> <code class="parameter">$column_key</code></span>, <span class="methodparam"><span class="type"><span class="type">int</span>|<span class="type">string</span>|<span class="type">null</span></span> <code class="parameter">$index_key</code><span class="initializer"> = <strong><code>null</code></strong></span></span>): <span class="type">array</span></div>

  <p class="para rdfs-comment">
   <span class="function"><strong>array_column()</strong></span> 返回
   <code class="parameter">array</code> 中键名为
   <code class="parameter">column_key</code> 的一列值。 如果指定了可选参数
   <code class="parameter">index_key</code>，则使用输入数组中
   <code class="parameter">index_key</code> 列的值将作为返回数组中对应值的键。
  </p>
 </div>

 <div class="refsect1 parameters" id="refsect1-function.array-column-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>
    
     <dt>
<code class="parameter">array</code></dt>

     <dd>

      <p class="para">
       多维数组或对象数组，从中提取一列值。
       如果提供的是对象数组，只有 public 的属性会被直接取出。
       如果想取出 private 和 protected 的属性，类必须实现
       <span class="function"><strong>__get()</strong></span> 和 <span class="function"><strong>__isset()</strong></span> 魔术方法。
      </p>
     </dd>

    
    
     <dt>
<code class="parameter">column_key</code></dt>

     <dd>

      <p class="para">
       需要返回值的列。它可以是索引数组的列索引，或者是关联数组的列的键，也可以是属性名。
       也可以是 <strong><code>null</code></strong> ，此时将返回整个数组（配合
       <code class="parameter">index_key</code> 参数来重新索引数组时非常好用）。
      </p>
     </dd>

    
    
     <dt>
<code class="parameter">index_key</code></dt>

     <dd>

      <p class="para">
       作为返回数组的索引/键的列。它可以是该列的整数索引，或者字符串键值。
       该值会像数组键一样被 <a href="language.types.array.html#language.types.array.key-casts" class="link">强制转换</a>
       （但是，在 PHP 8.0.0 之前，也被允许支持转换为字符串对象）。
      </p>
     </dd>

    
   </dl>

  </p>
 </div>

 <div class="refsect1 returnvalues" id="refsect1-function.array-column-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   返回输入数组中单列值的数组。
  </p>
 </div>

 <div class="refsect1 changelog" id="refsect1-function.array-column-changelog">
  <h3 class="title">更新日志</h3>
  <p class="para">
   <table class="doctable informaltable">
    
     <thead>
      <tr>
       <th>版本</th>
       <th>说明</th>
      </tr>

     </thead>

     <tbody class="tbody">
      <tr>
       <td>8.0.0</td>
       <td>
        <code class="parameter">index_key</code> 参数指定的列中的对象不再强制转换为字符串，而是会抛出
        <span class="classname"><a href="class.typeerror.html" class="classname">TypeError</a></span>。
       </td>
      </tr>

     </tbody>
    
   </table>

  </p>
 </div>

 <div class="refsect1 examples" id="refsect1-function.array-column-examples">
  <h3 class="title">范例</h3>
  <p class="para">
   <div class="example" id="example-4895">
    <p><strong>示例 #1 从结果集中取出 first_name 列</strong></p>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /></span><span style="color: #FF8000">//&nbsp;表示从数据库返回的记录集的数组<br /></span><span style="color: #0000BB">$records&nbsp;</span><span style="color: #007700">=&nbsp;array(<br />&nbsp;&nbsp;&nbsp;&nbsp;array(<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'id'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #0000BB">2135</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'first_name'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #DD0000">'John'</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'last_name'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #DD0000">'Doe'</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;),<br />&nbsp;&nbsp;&nbsp;&nbsp;array(<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'id'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #0000BB">3245</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'first_name'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #DD0000">'Sally'</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'last_name'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #DD0000">'Smith'</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;),<br />&nbsp;&nbsp;&nbsp;&nbsp;array(<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'id'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #0000BB">5342</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'first_name'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #DD0000">'Jane'</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'last_name'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #DD0000">'Jones'</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;),<br />&nbsp;&nbsp;&nbsp;&nbsp;array(<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'id'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #0000BB">5623</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'first_name'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #DD0000">'Peter'</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #DD0000">'last_name'&nbsp;</span><span style="color: #007700">=&gt;&nbsp;</span><span style="color: #DD0000">'Doe'</span><span style="color: #007700">,<br />&nbsp;&nbsp;&nbsp;&nbsp;)<br />);<br />&nbsp;<br /></span><span style="color: #0000BB">$first_names&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">array_column</span><span style="color: #007700">(</span><span style="color: #0000BB">$records</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'first_name'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$first_names</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

    <div class="example-contents"><p>以上例程会输出：</p></div>
    <div class="example-contents screen">
<div class="cdata"><pre>
Array
(
    [0] =&gt; John
    [1] =&gt; Sally
    [2] =&gt; Jane
    [3] =&gt; Peter
)
</pre></div>
    </div>
   </div>
  </p>
  <p class="para">
   <div class="example" id="example-4896">
    <p><strong>示例 #2 
     从结果集中总取出 last_name 列，用相应的“id”作为键值
    </strong></p>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /></span><span style="color: #FF8000">//&nbsp;使用示例&nbsp;#1&nbsp;中的&nbsp;$records&nbsp;数组<br /></span><span style="color: #0000BB">$last_names&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">array_column</span><span style="color: #007700">(</span><span style="color: #0000BB">$records</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'last_name'</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'id'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">$last_names</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

    <div class="example-contents"><p>以上例程会输出：</p></div>
    <div class="example-contents screen">
<div class="cdata"><pre>
Array
(
    [2135] =&gt; Doe
    [3245] =&gt; Smith
    [5342] =&gt; Jones
    [5623] =&gt; Doe
)
</pre></div>
    </div>
   </div>
  </p>
  <p class="para">
   <div class="example" id="example-4897">
    <p><strong>示例 #3 
     username 列是从对象获取 public 的 &quot;username&quot; 属性
    </strong></p>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /><br /></span><span style="color: #007700">class&nbsp;</span><span style="color: #0000BB">User<br /></span><span style="color: #007700">{<br />&nbsp;&nbsp;&nbsp;&nbsp;public&nbsp;</span><span style="color: #0000BB">$username</span><span style="color: #007700">;<br /><br />&nbsp;&nbsp;&nbsp;&nbsp;public&nbsp;function&nbsp;</span><span style="color: #0000BB">__construct</span><span style="color: #007700">(</span><span style="color: #0000BB">string&nbsp;$username</span><span style="color: #007700">)<br />&nbsp;&nbsp;&nbsp;&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">$this</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">username&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">$username</span><span style="color: #007700">;<br />&nbsp;&nbsp;&nbsp;&nbsp;}<br />}<br /><br /></span><span style="color: #0000BB">$users&nbsp;</span><span style="color: #007700">=&nbsp;[<br />&nbsp;&nbsp;&nbsp;&nbsp;new&nbsp;</span><span style="color: #0000BB">User</span><span style="color: #007700">(</span><span style="color: #DD0000">'user&nbsp;1'</span><span style="color: #007700">),<br />&nbsp;&nbsp;&nbsp;&nbsp;new&nbsp;</span><span style="color: #0000BB">User</span><span style="color: #007700">(</span><span style="color: #DD0000">'user&nbsp;2'</span><span style="color: #007700">),<br />&nbsp;&nbsp;&nbsp;&nbsp;new&nbsp;</span><span style="color: #0000BB">User</span><span style="color: #007700">(</span><span style="color: #DD0000">'user&nbsp;3'</span><span style="color: #007700">),<br />];<br /><br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">array_column</span><span style="color: #007700">(</span><span style="color: #0000BB">$users</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'username'</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

    <div class="example-contents"><p>以上例程会输出：</p></div>
    <div class="example-contents screen">
<div class="cdata"><pre>
Array
(
    [0] =&gt; user 1
    [1] =&gt; user 2
    [2] =&gt; user 3
)
</pre></div>
    </div>
   </div>
  </p>
  <p class="para">
   <div class="example" id="example-4898">
    <p><strong>示例 #4 
     通过 <span class="function"><strong>__get()</strong></span> 魔术方法从对象中获取 private 属性的 &quot;name&quot; 列。
    </strong></p>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br /><br /></span><span style="color: #007700">class&nbsp;</span><span style="color: #0000BB">Person<br /></span><span style="color: #007700">{<br />&nbsp;&nbsp;&nbsp;&nbsp;private&nbsp;</span><span style="color: #0000BB">$name</span><span style="color: #007700">;<br /><br />&nbsp;&nbsp;&nbsp;&nbsp;public&nbsp;function&nbsp;</span><span style="color: #0000BB">__construct</span><span style="color: #007700">(</span><span style="color: #0000BB">string&nbsp;$name</span><span style="color: #007700">)<br />&nbsp;&nbsp;&nbsp;&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">$this</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">name&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">$name</span><span style="color: #007700">;<br />&nbsp;&nbsp;&nbsp;&nbsp;}<br /><br />&nbsp;&nbsp;&nbsp;&nbsp;public&nbsp;function&nbsp;</span><span style="color: #0000BB">__get</span><span style="color: #007700">(</span><span style="color: #0000BB">$prop</span><span style="color: #007700">)<br />&nbsp;&nbsp;&nbsp;&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return&nbsp;</span><span style="color: #0000BB">$this</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">$prop</span><span style="color: #007700">;<br />&nbsp;&nbsp;&nbsp;&nbsp;}<br /><br />&nbsp;&nbsp;&nbsp;&nbsp;public&nbsp;function&nbsp;</span><span style="color: #0000BB">__isset</span><span style="color: #007700">(</span><span style="color: #0000BB">$prop</span><span style="color: #007700">)&nbsp;:&nbsp;</span><span style="color: #0000BB">bool<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #007700">{<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;return&nbsp;isset(</span><span style="color: #0000BB">$this</span><span style="color: #007700">-&gt;</span><span style="color: #0000BB">$prop</span><span style="color: #007700">);<br />&nbsp;&nbsp;&nbsp;&nbsp;}<br />}<br /><br /></span><span style="color: #0000BB">$people&nbsp;</span><span style="color: #007700">=&nbsp;[<br />&nbsp;&nbsp;&nbsp;&nbsp;new&nbsp;</span><span style="color: #0000BB">Person</span><span style="color: #007700">(</span><span style="color: #DD0000">'Fred'</span><span style="color: #007700">),<br />&nbsp;&nbsp;&nbsp;&nbsp;new&nbsp;</span><span style="color: #0000BB">Person</span><span style="color: #007700">(</span><span style="color: #DD0000">'Jane'</span><span style="color: #007700">),<br />&nbsp;&nbsp;&nbsp;&nbsp;new&nbsp;</span><span style="color: #0000BB">Person</span><span style="color: #007700">(</span><span style="color: #DD0000">'John'</span><span style="color: #007700">),<br />];<br /><br /></span><span style="color: #0000BB">print_r</span><span style="color: #007700">(</span><span style="color: #0000BB">array_column</span><span style="color: #007700">(</span><span style="color: #0000BB">$people</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'name'</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

    <div class="example-contents"><p>以上例程会输出：</p></div>
    <div class="example-contents screen">
<div class="cdata"><pre>
Array
(
    [0] =&gt; Fred
    [1] =&gt; Jane
    [2] =&gt; John
)
</pre></div>
    </div>
   </div>
   如果不提供 <span class="function"><strong>__isset()</strong></span>，会返回空数组。
  </p>
 </div>


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